A034301010

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A034301010

  1. 1. International Journal of Computational Engineering Research||Vol, 03||Issue, 4||www.ijceronline.com ||April||2013|| Page 1Fault Impact Assessment on Indirect Field Oriented Control forInduction Motor1,R.Senthil kumar, 2,R.M.Sekar, 3,L.Hubert Tony Raj, 4,I.Gerald ChristopherRaj1,PG scholar, Department of EEE, PSNA College of Engineering & Technology Dindigul – 624 622, Tamilnadu,India.2,Associate Professor, Department of EEE, PSNA College of Engineering & Technology Dindigul – 624 622,Tamilnadu, India.3,PG scholar, Department of EEE, PSNA College of Engineering & Technology Dindigul – 624 622, Tamilnadu,India.4,Associate Professor, Department of EEE, PSNA College of Engineering & Technology Dindigul – 624 622,Tamilnadu, India.I. INTRODUCTIONReliability assessment of motor drives is essential, especially in electric transportation applications.Safety is a major concern in such applications, and it is tied directly to re-liability. Induction machines, due totheir reliability and low cost, are widely used in industrial applications. However, several electro-mechanicalfaults may occur during their life span. In industry, most failures interrupt a process and finally reduce or evenstop the production. Thus, expensive scheduled maintenance is performed in order to prevent sudden failure andavoid economic damage[1].The computer simulation for these various modes of operation is conveniently obtained from theequations which describe the symmetrical induction machine in an arbitrary reference frame [2]. As in Fig. 1[3]shows entire block diagram of induction motor drive. To control the rotor which creates torque equation iscalled as rotor flux DQ model. while faults in supply voltage that is affected on stator voltage. that is not affectedon rotor voltage. Because rotor voltage produced due to electromagnetic induction principle. So rotor flux DQmodel is used. stator and synchronous reference frame is applicable for squirrel cage induction motor[2].because rotor part in short circuited in squirrel cage induction motor.The rotor reference frame is applicable forslip ring orFig. 1. Typical Induction Motor DriveABSTRACT:This paper presents an induction motor drives operating under indirect field-oriented controlin which rotor flux DQ axis model is used. In this model, various faults are analyzed such as voltage,current, speed and torque, stator flux. To develop the model, faults are first identified, and then, asimulation model of the setup is developed. Faults are injected into the model in sequential levels andthe system performance is assessed after each fault. Here rotor flux DQ model of induction motor isdeveloped and it’s controlled by using indirect field oriented control is studied.Here IFOC with DQmodel was simulated using MATLAB/ SIMULINK software. Also the waveforms of voltage, current,speed, torque, Q axis and D axis stator flux are obtained. The above faults are analyzed and rectifiedwhich results in the increase of efficiency. This analysis is shown to be simple and useful for assessingthe reliability of motor drives.Keywords : Fault impact assessment, Induction motor drive, Rotor flux DQ axis model,openloop andclosedloop IFOC
  2. 2. Fault Impact Assessment On Indirect…www.ijceronline.com ||April||2013|| Page 2wound rotor induction motor. Here synchronous reference frame is presented. because while converting3 phase to 2 phase which all parts considering DC quantity and control method is simple. The d-axis componentis aligned with the rotor flux vector and regarded as the flux-producing current component. On the other hand, theq-axis current, which is perpendicular to the d-axis, is solely responsible for torque production.Based on thepioneering work of Blaschke, high performance induction motor drives have been developed in recent decades.The high dynamic performance is achieved using the field-orientation theory which requires controlling the statorcurrent vector relative to the rotor flux [4].The indirect field oriented control method is essentially the same asdirect oriented control, except the unit vector signals are generated in feed forward manner [5]. Indirect fieldoriented control is very popular in industries IFOC being more commonly used because in closed-loop mode suchdrives more easily operate throughout the speed range from zero speed to high-speed field-weakening in DFOC,flux magnitude and angle feedback signals are directly calculated using so-called voltage or current models.In thispaper, a complete framework for induction motor under indirect field oriented control (IFOC) is presented. Herecover the faults in voltage, current, speed, torque, Q and D axis stator flux. In this paper change thevoltage and to study can be carried out to motor performance.II. DYNAMIC MODEL OF INDUCTION MOTORThe dynamic model model of squirrel cage induction motor[SEIM] in stationary reference frame in α-β reference frame variables [6].Fig. 2. Equivalent Circuit of SCIM (a) α axis (b) β axisComponents stator and rotor voltage of the induction motor can be expressed as follows:(1)(2)(3)(4)The components of rotor flux linkage in the stationary reference can be written as+ (5)+ (6)Where and are the residual rotor flux linkages in α-β axis, respectively.Then, with an electrical rotor speed of ,the components of rotating voltage in the stationary referenceframe are as the follows:(7)(8)The expressions for capacitor voltages are,(9)
  3. 3. Fault Impact Assessment On Indirect…www.ijceronline.com ||April||2013|| Page 3(10)Using Fig. 2 equations (1)-(10), for the matrix equations of SCIM at no-load in the stationary reference frameare given by=(11)From (11), can be written the state equations as follows:(12)Where,A = , B =,I. INDUCTION MOTOR MODEL IN DQ0 SYNCHRONOUS REFERENCE FRAMESFig. 3. Change of variables 3Φ to 2Φ conversionUsing Fig. 3[7] Synchronous frame induction motor equations are given as eqn 13 to eqn 17.Stator voltage equations:(13)Rotor voltage equations:(14)Where,
  4. 4. Fault Impact Assessment On Indirect…www.ijceronline.com ||April||2013|| Page 4= (15)Torque Equations:Nm (16)III. INDIRECT FIELD ORIENTED CONTROL OF INDUCTION MOTORFig. 4 shows the block diagram of indirect field orientation control strategy with sensor in which speedregulation is possible using a control loop.Fig. 4. Indirect Field-Oriented Control for Induction Motor DrivesIn IFOC, flux space angle feed forward and flux magnitude signals first measure stator currents and rotor speedfor then deriving flux space angle proper by summing the rotor angle corresponding to the rotor speed and thecalculated reference value of slip angle corresponding to the slip frequency. An induction motor drive underIFOC requires measurements of the three-phase currents and speeds and has two control inputs for torque, orspeed, androtor flux[8].p = 0 steady state (17)= (18)(19)(20)The reference currents of the q-d-o axis ( , ) are converted to the reference phase vlotages ( , ) asthe commanded voltages for the control loop.By using ,which is shown in equation(17) and using actualrotor speed, the rotor flux position is obtained.(21)or(22)As shown in Fig. 4., two-phase current feeds the Clarke transformation block. These projection outputsare indicated as and . These two components of the current provide the inputs to Park’s transformation,which gives the currents in the excitation reference frame. The and components, which are outputsof the Park transformation block, are compared to their reference values , the flux reference, and , thetorque reference. The torque command, , comes from the output of the speed controller. The flux command,, is the output of the flux controller which indicates the right rotor flux command for every speed reference.Magnetizing current is usually between 40 and 60% of the nominal current. For operating in speeds abovethe nominal speed, a field weakening section should be used in the flux controller section. The current regulatoroutputs, and are applied to the inverse Park transformation.The outputs of this block are the signals thatdrive the inverter.
  5. 5. Fault Impact Assessment On Indirect…www.ijceronline.com ||April||2013|| Page 5IV. MOTOR DRIVE, FAULTS AND PERFORMANCEA. System OverviewAs in Fig. 4 faults can occur in the following six possible subsystems or components:[1] Faults due to voltage variations[2] Faults due to current variations[3] Faults due to speed variations[4] Faults due to load torque variations[5] Faults due to Q axis Stator Flux Variations[6] Faults due to D axis Stator Flux VariationsB. Voltage VariationIn this paper to change the voltage and to study can be carried out to motor performance. To control theinduction motor by using indirect field oriented control method. Many problems are a result of high or lowvoltage, unbalanced voltage, ungrounded power systems, or voltage spikes[9].V. SIMULATION AND EXPERIMENTSSome of the faults could damage the experimental setup and cannot be tested directly. Also, manycommercial motor drives have built-in protection circuitry and algorithms that take action after a fault by shuttingdown or otherwise altering operation. It is not easy (or advisable) to override protection, but fault modes used herecan also integrate protection in several aspects.. Even though the simulations here do not model or cover allphysical dynamics, noise, vibration, power loss, and nonlinearities of material, they provide a useful tool thatcan save the cost of rebuilding a motor drive, or most other systems, after severe failures.A. SimulationsSimulations provide a safe environment to evaluate even the most extreme faults, provided a simulationhas been validated in hardware. Some commercial drives have fault detection and isolation, which would not behelpful if the target is to observe drive performance under faults, Simulations of the IFOC induction motordrive shown in Fig. 4 were performed in MATLAB/SIMULINK for a 1.5-hp induction machine. The inverterinvolved IGBT–diode pairs from the SimPowerSystems Toolbox in SIMULINK.For the implementation of thestate space equations of a system model, MATLAB/ SIMULINK. has the denominated user defined functions ors-functions [10]. In these blocks the code that defines the model in state equations can be written. In this code somuch is defined the number of inputs and outputs, like the states and the state space equations of the system.This s-function will correspond to a block with the inputs, outputs and parameters shown in Fig. 5. The s-function can be called from a MATLAB/SIMULINK s-function block. In Fig. 5,one is the SIMULINK blockdiagram where “VSI-IM model” is the s-function that call’s the defined function. The inputs are multiplexed ina bus can be demultiplexed, and the same occurs for the outputs.Here rotor flux DQ model of induction motoris presented in programmed manner by using M-File.and fault analysis also written in the same M-File. Whilechanging the voltage it will affect current, speed, torque and flux.TABLE I. MACHINE PARAMETERSSl.no Machine Parameters in perunit1 Stator resistance Rs = 0.012 Rotor resistance Rr = 0.023 Stator leakage inductance Lsl =0.14 Rotor leakage inductance Lrl =0.15 Magnetizing inductance Lm = 4.56 Load torque Tl = 0.23757 Supply voltage Vs =1.0
  6. 6. Fault Impact Assessment On Indirect…www.ijceronline.com ||April||2013|| Page 6Fig. 5. Simulation Diagram of Induction Motor Under Open Circuit ConditionFig 6.Voltage Response of Induction Motor Under Fault ConditionFig. 7. Current Response of Induction Motor Under Fault ConditionFig. 8.Speed Response of Induction Motor Under Fault ConditionFig 9.Load Torque Response of Induction Motor Under Fault Condition
  7. 7. Fault Impact Assessment On Indirect…www.ijceronline.com ||April||2013|| Page 7Fig. 10. Q axis Stator Flux Response of Induction Motor Under Fault ConditionFig. 11. D axis Stator Flux Response of Induction Motor Under Fault ConditionFig. 12. Simulation Diagram of Closed loop IFOCFig. 13. Speed Response of Induction Motor Under Normal ConditionFig. 14. Torque Response of Induction Motor Under Normal Condition
  8. 8. Fault Impact Assessment On Indirect…www.ijceronline.com ||April||2013|| Page 8Fig. 15. Currents Response of Induction Motor Under Normal ConditionFig. 16. Speed of Induction Motor Under Fault ConditionFig. 17. Torque Response of Induction Motor Under Fault ConditionFig. 18. Currents Response of Induction Motor Under Fault ConditionB. Simulation ResultsThe drive architectures of Fig.5 have been completely implemented and assessed in the , MATLAB/SIMULINK environment along with their respective control systems. The simulation is based on the parametersshown in Table I. A simulation study based on the model shown in Fig. 6 is carried out to compare open loopIFOC. The following figures shows waveforms of voltage, current, speed, torque and flux under faultconditions.As in Fig. 6,at normal condition there is no disturbance between 0 to 1.when the fault occurs atpoint1,suddenly the voltage was dipped between 1 to 2.After 2,the fault was recovered so it maintain steadystate condition. As in Fig. 7,at normal condition there is no disturbance between 0 to 1.when the fault occurs atpoint 1 suddenly the current was reached 0 between 1 to 2.After 2,the fault was recovered, in that point suddenlythe current was increased more than rated current. Because current transients will occur.so it reaches steady stateat 2.2.As in Fig. 8, at normal condition there is no disturbance between 0 to 1.when the fault occurs at point1,suddenly the voltage was decreased between 1 to 2.After 2, the fault was recovered, in that point the speed notreaches steady state at point 2.It takes some time to reach steady state. So it reaches steady state at 2.2.As in Fig.9,at normal condition there is no disturbance between 0 to 1.when the fault occurs at point 1 suddenly the torquewas reached 0 between 1 to 2.After 2,the fault was recovered, in that point suddenly the torque was increasedmore than rated torque. so oscillations will occur. It takes some time to reach steady state. So it reaches steadystate at 2.2.As in Fig. 10,at normal condition there is no disturbance between 0 to 1.
  9. 9. Fault Impact Assessment On Indirect…www.ijceronline.com ||April||2013|| Page 9when the fault occurs at point 1 suddenly the Q axis stator flux was reached 0 between 1 to 2.After2,the fault was recovered, in that point suddenly the flux was increased more than rated flux. so oscillations willoccur. It takes some time to reach normal state. So it reaches steady state at 2.2. As in Fig. 11, at normalcondition there is no disturbance between 0 to 1.when the fault occurs at point 1 suddenly the D axis stator fluxwas reached 0 between 1 to 2.After 2,the fault was recovered, in that point suddenly the flux was increased morethan rated flux. so oscillations will occur. It takes some time to reach normal state. So it reaches steady state at2.2.C. Experimental EnvironmentThe experimental setup includes all control, power electronics, motor, load, and measurements. Thecontrol and some measurements are available on an eZdspF2812 platform which is based on a TexasInstruments TMS320F2812 DSP. This control platform is integrated into the Grainger Center Modular Inverter[11] which also includes an inverter power stage rated at 400V and 100A. A dynamometer is used to set the loadtorque. Measurements include speed, torque, currents, voltages, and input and output power. All control andmeasurement devices, including the dynamometer, are controlled using MATLAB/ Simulink through theSimulink Real-Time Workshop. Communication between the software and the DSP occurs through real-timedata exchange (RTDX) via a parallel port. Here fault monitoring kit is also needed to analyze various faults.There are two factors are considered. The first factor is to avoid injecting faults that could cause severe failuresor trigger the protection circuitry as predicted from simulations. The second factor is to use a tight externalclosed-loop torque control in experiments to avoid sudden overload conditions on the dynamometer and themotor shaft. The experimental setup is shown in Fig. 13,Fig. 19. Experimental setup for model validation.VI. CONCLUSIONThe Existing methodology for reliability modeling covers essential faults in a drive system, includingthe machine, power electronics converters, and sensors. The methodology leads to rotor flux DQ model of aninduction motor drive under open loop IFOC and can be extended to other drives or to more faults in othercomponents. A model was validated in experiments and used for the complete procedure. The survivor functionof the complete system was found analytically including fault coverage. Simplifications were proposed based ondominant fault modes, which were found to be faults in the voltage, current, speed, load torque and stator flux.Further research could apply this methodology to other drive topologies, more components in any topology(e.g., link capacitors, gate drives, etc.), design of fault tolerance, and actual field failure rates. Even though DQ’smodel might not be accurate since faults generally vary with time, the proposed methodology serves the purposeof a comprehensive, straightforward, and versatile reliability modeling procedure. Thus the open loop andclosed loop IFOC with DQ model is simulated using MATLAB/ SIMULINK.REFERENCES[1] Ali. M. Bazzi, Alejandro Dominguez-Garcia, and Philip T. Krein,“Markov Reliability Modeling for Induction Motor DrivesUnder Field-Oriented Control,” IEEE Trans. Power Electron., Vol, No. 2, feb 2012.[2] P. C Krause and C. H Thomas, ”Simulation of Symmetrical Induction Machinery” IEEE Trans., Power Apparatus and SystemsVol. PAS-84, No. 11,1965[3] A. M. Bazzi, A. D. Dominguez-Garcia, and P. T. Krein “A method for impact assessment of faults on the performance offield oriented control drives: A first step to reliabilty modeling” in Proc. IEEE Appl. power Electron. Conf. Expo., 2010,pp. 256–263[4] Zsolt Beres and Peter Vranka, ”Sensor less IFOC of Induction Motor With Current Regulators in Current Reference Frame”IEEE Trans. Ind. Appl., Vol. 37, No.4.2001.[5] Alfio consoli, Giuseppe Scarcella and Antonio Testa,”Slip Frequency Detection for Indirect Field Oriented Control Drives”IEEE Trans. Ind. Appl., Vol, No.1.,2004.
  10. 10. Fault Impact Assessment On Indirect…www.ijceronline.com ||April||2013|| Page 10[6] G . R .Slemon, “ Modeling of Induction Machines for Electric Drives” IEEE Trans. Ind. Appl., Vol. 25, No.6, pp. 1126-1131,Nov/Dec 1989.[7] S. Green, D. J. Atkinson, A. G. Jack, B. C. Mecrow, and A. king, “ Sensor less operation of a Operation of a Fault TolerantPM Drive,” IEE Proc. Elect. Power Appl., Vol. 150, No.2,pp.117-125,Mar.2003[8] Naceri Farid, Belkacem Sebti, Kercha Memberka and Benmokrane Tayed, “Performance Analysis of Field- Oriented Controland Direct Torque Control for Sensorless Induction Motor Drives” in Proc. 15thMediterranean Conf., on Contol & Automation,July 2007.[9] W. R. Finley, M. M. Hodowanec, W.G. Holter, “ An Analytical Approach to Solving Motor Vibration Problems” IEEE PCICConf., Sep 1999.[10] Bin Wu, S. B. Dewan and G. R. Slemon,” PWM CSI Inverter Induction Motor Drives” IEEE Trans. Ind. Appl., Vol.28, No.1.pp 64-71, 1992[11] J. Kimball, M. Amerhein, A. Kwansinki, J. Mossoba, B. Nee, Z. Sorchini, W. Weaver, J. Weels and G. Zhang, “ModularInverter for Advanced Control Applications” Technical Report CEME-TR-200-01, University of Illinois May 2006.

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